In dogs, insulin which has been shown to be the major hepatotrophic substance in the splanchnic venous blood will be infused into the portal or hepatic arterial circulation with or without glucagon in an effort to expedite recovery from acute ischemic or chemical liver injury. After portacaval shunt, attempts will also be made with these hormones to control the hepatic synthesis of cholesterol, triglycerides and other lipid moieties. If substantial influences are demonstrated upon hepatic regenerative and metabolic processes, systemic hormone administration in different doses and combinations will be tried. A final objective might be the control of serum lipids and the possible reversal of experimental atherosclerosis by changing the whole animal's hormone environment with chronic hormone infusions.